Climate Gate Post 2 — The Hockey Stick

Our last episode ended with a retired minerals consultant/consultant to big oil and his sidekick, economics professor and fellow at the right-wing think tank The Fraser Institute, getting all hot under the collar about a graph adapted from an article by Mann, Bradley and Hughes (1998) used in the TAR: the infamous “Hockey Stick”:

They lamented the absence of the medieval warm period. To them, it contradicted an older less precise (by a long shot) graphic used in the First IPCC Assessment report.

In 2003, McIntyre and McKittrick published an article that challenged the methods and findings of the MBH(* paper used in the TAR.

From the paper:

The particular “hockey stick” shape derived in the MBH98 proxy construction – a temperature index that decreases slightly between the early 15th century and early 20th century and then increases dramatically up to 1980 — is primarily an artefact of poor data handling, obsolete data and incorrect calculation of principal components.

“Through Monte Carlo analysis, we show that MBH98 benchmarks for significance of the Reduction of Error (RE) statistic are substantially under-stated and, using a range of cross-validation statistics, we show that the MBH98 15th century reconstruction lacks statistical significance.”

So, we see some back and forth between Mann et. al and others in the climate science community and M&M over the use of certain statistical analysis, PC, to analyze paleoclimate data. Not only did they reject the use of PC analysis, but also the use of a specific set of paleoclimate data, Bristlecone Pines.

Once more unto the breach, dear friends, once more,
Or close the wall up with our English dead!
In peace there's nothing so becomes a man
As modest stillness and humility;
But when the blast of war blows in our ears,
Then imitate the action of the tiger:
Stiffen the sinews, summon up the blood.
"Henry V" (5.3.44-51)